A number of studies ahve shown that treatment of patients with hyprlipidemia and established coronary artery disease (CAD results in marked reduction of subsequent clinical events such as myocardial infarction (MI) and death, in spite of small amounts of improvement in angiographic degree of stenosis. Not only is the mechanism causing this discrepancy unclear, the lack of a surrogate for clinical events makes studies of the benefits of lipid lowering therapy difficult. We will examine the effect of intravascular ultrasound, and on epicardial vessel endothelial function and resistance vessel function in the coronary circulation assessed by the response to acetylcholine and adenosine, in subjects will be patients with known and documented coronary artery disease, and a moderately elevated LDL cholesterol level.